CN111638585A

CN111638585A - Optical assembly, image capturing module and mobile terminal

Info

Publication number: CN111638585A
Application number: CN201910155259.6A
Authority: CN
Inventors: 谢晗; 邹海荣; 刘彬彬
Original assignee: OFilm Tech Co Ltd
Current assignee: Nanchang OFilm Precision Optical Products Co Ltd; OFilm Group Co Ltd
Priority date: 2019-03-01
Filing date: 2019-03-01
Publication date: 2020-09-08

Abstract

The invention relates to an optical assembly, an image capturing module and a mobile terminal. The optical assembly sequentially comprises a first lens with positive refractive power from an object side to an image side, and the object side surface of the first lens is a convex surface at an optical axis; the second lens element with negative refractive power has a concave image-side surface at the optical axis; a third lens element with positive refractive power having a convex image-side surface at an optical axis; a fourth lens element with refractive power; a fifth lens element with refractive power; a sixth lens element with refractive power; the image side surface of the seventh lens element is concave at the optical axis, at least one inflection point exists on the image side surface of the seventh lens element, and both the object side surface and the image side surface of the seventh lens element are aspheric surfaces; the optical assembly also satisfies the relationship: f/EPD < 2.0. When the above relationship is satisfied, the optical module has a characteristic of a large amount of light flux.

Description

Optical assembly, image capturing module and mobile terminal

Technical Field

The present invention relates to the field of optical imaging, and in particular, to an optical assembly, an image capturing module and a mobile terminal.

Background

With the development of portable electronic products such as smart phones and tablet computers, the market demands for miniaturization and imaging quality of camera lenses on the portable electronic products are gradually increased. Among these, the photosensitive elements commonly used for acquiring images are typically both Charge Coupled Devices (CCD) or complementary metal oxide semiconductor sensors (CMOS). However, the imaging quality of a general photosensitive element is significantly degraded in environments with insufficient light, such as dusk and rainy days, and therefore, an image pickup lens with a large light flux is urgently needed.

Disclosure of Invention

Accordingly, it is desirable to provide an optical assembly, an image capturing module and a mobile terminal for achieving a large light flux.

An optical assembly comprising, in order from an object side to an image side:

the optical lens comprises a first lens element with positive refractive power, a second lens element with negative refractive power, and a third lens element with positive refractive power, wherein the object-side surface of the first lens element is convex at the optical axis;

the second lens element with negative refractive power has a concave image-side surface at an optical axis;

a third lens element with positive refractive power having a convex image-side surface at an optical axis;

a fourth lens element with refractive power;

a fifth lens element with refractive power;

a sixth lens element with refractive power;

the image side surface of the seventh lens element is concave at an optical axis, at least one inflection point exists on the image side surface of the seventh lens element, and both the object side surface and the image side surface of the seventh lens element are aspheric surfaces;

the optical assembly further satisfies the following relationship:

f/EPD＜2.0；

where f is the total effective focal length of the optical assembly and EPD is the entrance pupil diameter of the optical assembly.

When the f/EPD relation is satisfied, under the same specification of the total effective focal length, the optical assembly has a larger entrance pupil diameter (clear aperture) to have the characteristic of large light transmission amount, so that the imaging quality in environments with insufficient light such as dusk and rainy days is improved. In addition, because the optical assembly has a larger entrance pupil diameter, the effective half aperture of the object side surface of the first lens is correspondingly enlarged, so that the optical assembly has larger light transmission quantity.

In one embodiment, the optical assembly satisfies the following relationship:

1.50＜SD72/SD11＜3.00；

wherein SD11 is the distance from the optical axis at the maximum effective diameter of the object-side surface of the first lens (effective half aperture), and SD72 is the distance from the optical axis at the maximum effective diameter of the image-side surface of the seventh lens.

When the relationship of SD72/SD11 is satisfied, the ratio of the effective half aperture of the image side surface of the seventh lens to the effective half aperture of the object side surface of the first lens can be restrained, the effective half aperture of the image side surface of the seventh lens is prevented from being too large, and the seventh lens is closer to the imaging surface than other lenses, so that the outer diameter of the seventh lens can be reduced while the large light transmission amount is satisfied (when the seventh lens is packaged and molded with a photosensitive chip, the module volume from the seventh lens to the photosensitive chip part can be reduced), and the miniaturization design of the optical assembly is realized. Synchronously, when the effective half aperture of the object side surface of the first lens is enlarged, the effective half aperture of the image side surface of the seventh lens is correspondingly enlarged, so that the relative illumination of the off-axis field is improved. When the relationship of SD72/SD11 is lower than the lower limit, the effective half aperture of the image side surface of the seventh lens is excessively compressed, so that marginal rays are easily blocked, and the relative illumination of an off-axis field of view is reduced, thereby reducing the imaging quality of peripheral images; when the relationship of SD72/SD11 is higher than the upper limit, the effective half aperture of the image side surface of the seventh lens is too large, so that the angle (CRA) at which light rays of the off-axis field of view enter the imaging plane is easily increased, which is not favorable for matching with a conventional photosensitive chip, and the resolution is reduced.

In one embodiment, the optical assembly satisfies the following relationship:

f2/f1＜-1.00；

wherein f1 is the focal length of the first lens, and f2 is the focal length of the second lens. The first lens element provides a strong positive refractive power, the second lens element is reasonably provided with a negative refractive power, and when the relationship is satisfied, the optical assembly can correct part of spherical aberration generated by the first lens element, so that the imaging quality is improved; in addition, sufficient positive refractive power can be configured at the object side end (the first lens element and the second lens element) of the optical element, so that the optical element has better ability of balancing field curvature, and the length of the optical element in the optical axis direction can be favorably compressed.

In one embodiment, the optical assembly satisfies the following relationship:

0＜f123/f＜2.00；

wherein f123 is a composite focal length of the first lens, the second lens, and the third lens. The refractive power coordination of the first lens element, the second lens element and the third lens element can be optimized when the above relation is satisfied, the first lens element provides positive refractive power, the second lens element provides negative refractive power to correct spherical aberration, and the third lens element provides positive refractive power in coordination with the first lens element, so that the deflection angle of light rays can be effectively controlled, and the sensitivity of the optical assembly can be reduced; in addition, the combination of the three lenses is equivalent to a lens with positive refractive power, enough refractive power can be configured at the object side end for imaging, and the second lens with negative refractive power can be used for correcting spherical aberration so as to improve the imaging quality.

In one embodiment, the optical assembly satisfies the following relationship:

1.20＜TTL/ImgH＜2.00；

wherein ImgH is a half of a diagonal length of an effective pixel area of the optical assembly on an imaging surface, and TTL is a distance on an optical axis from an object-side surface of the first lens element to the imaging surface of the optical assembly. When the chips with the same size (the same imaging area) are matched to form the module, the optical component meeting the ratio relation can effectively compress the length of the module in the optical axis direction, so that the miniaturization design is realized. In addition, when the ratio is lower than the lower limit, the thickness of each lens is excessively compressed, which is not favorable for practical production and processing; when the ratio is higher than the upper limit, the length of the module in the optical axis direction is too long, which is not favorable for miniaturization design.

In one embodiment, the optical assembly satisfies the following relationship:

-15.00＜(R22+R31)/(R22-R31)＜0；

wherein R22 is a curvature radius of the image side surface of the second lens at the optical axis, and R31 is a curvature radius of the object side surface of the third lens at the optical axis. When the relation is met, the curvature radiuses of the image side surface of the second lens and the curvature radiuses of the object side surface of the third lens at the optical axis can be reasonably configured, so that the deflection angle of light rays which are emitted out of the first lens and then enter the second lens is effectively reduced, the sensitivity of the optical assembly is reduced, and the generation of ghost images can be effectively inhibited.

In one embodiment, the optical assembly satisfies the following relationship:

3.00＜f/R72＜4.00；

wherein R72 is a radius of curvature of an image-side surface of the seventh lens element at an optical axis. The image side surface of the seventh lens has a tendency of changing from concave to convex from the optical axis to the circumference, the change tendency can better balance chromatic aberration of an off-axis field of view, and when the relation is satisfied, the ratio of the total effective focal length f to R72 can be reasonably configured, so that the astigmatism contribution ratio of the seventh lens is in a reasonable range, and the optical assembly obtains good imaging quality.

In one embodiment, the optical assembly satisfies the following relationship:

2.00＜CT1/CT2＜4.00；

wherein CT1 is the thickness of the first lens element on the optical axis, and CT2 is the thickness of the second lens element on the optical axis. When satisfying above-mentioned relation, can optimize first lens with the central thickness of second lens shortens optical component is in the ascending length of optical axis direction, and does benefit to first lens with the machine-shaping of second lens ensures fashioned stability.

In one embodiment, the optical assembly satisfies the following relationship:

0.05≤(T34+T56)/TTL≤0.15；

wherein T34 is a distance between the third lens element and the fourth lens element on the optical axis, T56 is a distance between the fifth lens element and the sixth lens element on the optical axis, and TTL is a distance between the object-side surface of the first lens element and the image plane of the optical assembly on the optical axis. When the relation is satisfied, the distance between the lenses can be reasonably configured, so that the length of the optical assembly in the optical axis direction is effectively compressed, and the optical assembly is favorable for production and assembly while high resolution is satisfied.

An image capturing module includes a photosensitive element and the optical assembly according to any of the above embodiments, wherein the photosensitive element is disposed on an image side of the optical assembly.

A mobile terminal includes the image capturing module described in the above embodiments.

Drawings

FIG. 1 is a schematic view of an optical assembly according to a first embodiment of the present invention;

fig. 2 is a spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%);

FIG. 3 is a schematic view of an optical assembly according to a second embodiment of the present invention;

FIG. 4 is a spherical aberration diagram (mm), an astigmatism diagram (mm) and a distortion diagram (%);

FIG. 5 is a schematic view of an optical assembly according to a third embodiment of the present invention;

FIG. 6 is a spherical aberration diagram (mm), an astigmatism diagram (mm) and a distortion diagram (%) -of the optical assembly in the third embodiment;

FIG. 7 is a schematic view of an optical assembly according to a fourth embodiment of the present invention;

FIG. 8 is a spherical aberration diagram (mm), an astigmatism diagram (mm) and a distortion diagram (%);

FIG. 9 is a schematic view of an optical assembly provided in a fifth embodiment of the present invention;

fig. 10 is a spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%);

FIG. 11 is a schematic view of an optical assembly according to a sixth embodiment of the present invention;

fig. 12 is a spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) -of the optical assembly in the sixth embodiment;

FIG. 13 is a schematic view of an optical assembly according to a seventh embodiment of the present invention;

fig. 14 is a spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) -of the optical assembly in the seventh embodiment;

fig. 15 is a schematic view of an image capturing module according to an embodiment of the present invention;

fig. 16 is a schematic diagram of a mobile terminal according to an embodiment of the present invention.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Referring to fig. 1, the optical assembly 10 in the present application includes, in order from an object side to an image side, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with refractive power, a fifth lens element L5 with refractive power, a sixth lens element L6 with refractive power, and a seventh lens element L7 with negative refractive power.

In some embodiments, the object side of the first lens L1 is further provided with a stop ST 0. By providing the stop ST0 on the object side of the first lens L1, the exit pupil can be made distant from the imaging plane, and the effective diameter of the optical assembly 10 can be reduced without reducing the telecentricity of the optical assembly 10, thereby achieving downsizing. In some embodiments, the stop ST0 is fixedly disposed on the object side surface S2 of the first lens L1, so that the length of the optical assembly 10 in the optical axis direction can be reduced, enabling a compact design.

The first lens L1 includes an object side surface S2 and an image side surface S3, the second lens L2 includes an object side surface S4 and an image side surface S5, the third lens L3 includes an object side surface S6 and an image side surface S7, the fourth lens L4 includes an object side surface S8 and an image side surface S9, the fifth lens L5 includes an object side surface S10 and an image side surface S11, the sixth lens L6 includes an object side surface S12 and an image side surface S13, and the seventh lens L539 7 includes an object side surface S14 and an image side surface S15.

Specifically, the object-side surface S2 of the first lens element L1 is convex along the optical axis, the image-side surface S5 of the second lens element L2 is concave along the optical axis, the image-side surface S7 of the third lens element L3 is convex along the optical axis, the image-side surface S15 of the seventh lens element L7 is concave along the optical axis, at least one inflection point exists on the image-side surface S15 of the seventh lens element L7, and the object-side surface S14 and the image-side surface S15 of the seventh lens element L7 are aspheric. The aspheric design can solve the problem of distortion of the field of view, and can also enable the lens to achieve excellent optical effects under the conditions of small size, thinness and flatness, thereby enabling the optical assembly 10 to be thinner and lighter. In some embodiments, the shape of the image-side surface S15 of the seventh lens L7 varies from the optical axis to the circumference, e.g., from concave to convex.

The image light of the object located on the object side of the first lens L1 passes through the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 in sequence, and is finally imaged on the imaging surface S18.

The aspherical surface type formulas of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are as follows:

wherein Z is a distance from a corresponding point on the aspherical surface to a plane tangent to the surface vertex, r is a distance from a corresponding point on the aspherical surface to the optical axis, c is a curvature of the aspherical surface vertex, k is a conic constant, and Ai is a coefficient corresponding to the i-th high-order term in the aspherical surface type formula.

In some embodiments, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7 are all made of plastic, and in this case, the plastic lens can reduce the weight of the optical assembly 10 and reduce the production cost. In some embodiments, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7 are made of glass, and thus the optical assembly 10 can endure higher temperature and has better optical performance. In other embodiments, only the first lens L1 may be made of glass, and the other lenses may be made of plastic, in which case, the first lens L1 closest to the object side can better withstand the influence of the ambient temperature on the object side, and the other lenses are made of plastic, so that the production cost of the optical assembly 10 is kept low.

In some embodiments, the optical assembly 10 is disposed with the infrared filter 110 made of glass, and the infrared filter 110 is disposed on the image side of the seventh lens element L7. The infrared filter 110 includes an object side S16 and an image side S17. The infrared filter 110 is used for filtering the light rays for imaging, and is specifically used for isolating infrared light to prevent the infrared light from reaching the imaging surface S18, thereby preventing the infrared light from affecting the color and the definition of a normal image and improving the imaging quality of the optical assembly 10.

In some embodiments, the optical assembly 10 satisfies the following relationship:

f/EPD＜2.0；

where f is the total effective focal length of the optical assembly 10, EPD is the entrance pupil diameter of the optical assembly 10, SD11 is the distance from the optical axis at the maximum effective diameter of the object-side surface S2 of the first lens L1, and SD72 is the distance from the optical axis at the maximum effective diameter of the image-side surface S15 of the seventh lens L7. In some of these embodiments, the f/EPD may be 1.47, 1.50, 1.55, 1.60, 1.64, 1.70, 1.75, 1.80, or 1.85. When the above-mentioned f/EPD relationship is satisfied, under the same specification of the total effective focal length, the optical element 10 has a larger entrance pupil diameter (clear aperture) to have the characteristic of a large light transmission amount, thereby improving the imaging quality in environments with insufficient light such as dusk and rainy days. In addition, since the optical module 10 has a larger entrance pupil diameter, the effective half aperture of the object-side surface S2 of the first lens L1 is correspondingly enlarged, so that the optical module 10 has a larger light transmission amount.

In some of these embodiments, the optical assembly 10 satisfies the following relationship:

1.50＜SD72/SD11＜3.00；

where SD11 is the distance from the optical axis at the maximum effective diameter of the object-side surface S2 of the first lens L1 (effective half aperture), and SD72 is the distance from the optical axis at the maximum effective diameter of the image-side surface S15 of the seventh lens L7. In some of these embodiments, SD72/SD11 may be 2.10, 2.20, 2.30, 2.40, 2.50, or 2.60. When the relationship of SD72/SD11 is satisfied, the ratio of the effective half aperture of the image-side surface S15 of the seventh lens L7 to the effective half aperture of the object-side surface S2 of the first lens L1 can be restrained, the effective half aperture of the image-side surface S15 of the seventh lens L7 is prevented from being excessively large, and since the seventh lens L7 is closer to the image-forming surface than the other lenses, the outer diameter of the seventh lens L7 can be reduced while a large light flux is satisfied (when the module volume from the seventh lens L7 to the photo-sensitive chip portion can be reduced when the photo-sensitive chip is packaged), thereby realizing the compact design of the optical module 10. Synchronously, when the effective half aperture of the object-side surface S2 of the first lens L1 is enlarged, the effective half aperture of the image-side surface S15 of the seventh lens L7 is also enlarged accordingly, thereby enhancing the relative illuminance of the off-axis field of view. When the relationship of SD72/SD11 is lower than the lower limit, the effective half aperture of the image side S15 of the seventh lens L7 is compressed excessively, so that marginal rays are easily blocked, and the relative illumination of an off-axis field is reduced, thereby reducing the imaging quality of peripheral images; when the relationship SD72/SD11 is higher than the upper limit, the effective half aperture of the image side surface S15 of the seventh lens L7 is too large, so that the angle (CRA) at which light rays of the off-axis field of view enter the imaging surface is easily increased, which is not favorable for matching with a conventional photo chip, and the resolution is reduced, and when the effective half aperture of the image side surface S15 of the seventh lens L7 is too large, the outer diameter of the seventh lens L7 is increased, which is not favorable for miniaturization design.

f2/f1＜-1.00；

where f1 is the focal length of the first lens L1, and f2 is the focal length of the second lens L2. In some of these embodiments, f2/f1 can be-3.70, -3.60, -3.50, -3.40, -2.50, -2.00, -1.90, or-1.80. The first lens element L1 provides a stronger positive refractive power, the second lens element L2 reasonably configures a negative refractive power, and when the above relationship is satisfied, the optical assembly 10 can correct part of the spherical aberration generated by the first lens element L1, thereby improving the imaging quality; in addition, sufficient positive refractive power can be disposed at the object-side end (the first lens element L1 and the second lens element L2) of the optical element 10, so that the optical element 10 has better ability to balance field curvature, and the length of the optical element 10 in the optical axis direction can be advantageously reduced.

0＜f123/f＜2.00；

where f123 is a combined focal length of the first lens L1, the second lens L2, and the third lens L3. In some of these embodiments, f123/f can be 1.00, 1.02, 1.05, 1.08, 1.10, 1.12, 1.14, or 1.16. The above relation is satisfied, and the cooperation of the refractive powers of the first lens element L1, the second lens element L2, and the third lens element L3 can be optimized, so that the deflection angle of light rays can be effectively controlled, and the sensitivity of the optical assembly 10 can be reduced; in addition, while balancing the aberrations, sufficient refractive power can be disposed at the object side (the first lens element L1, the second lens element L2, and the third lens element L3) to improve the image quality.

1.20＜TTL/ImgH＜2.00；

wherein ImgH is a half of a diagonal length of an effective pixel area of the optical device 10 on the imaging surface S18, and TTL is a distance on the optical axis from the object side surface S2 of the first lens element L1 to the imaging surface S18 of the optical device 10. In some of these embodiments, the TTL/ImgH may be 1.46, 1.47, 1.48, 1.49, or 1.50. When chips of the same size (the same imaging area) are matched to form a module, the optical assembly 10 satisfying the above ratio relationship can effectively compress the length of the module in the optical axis direction, thereby realizing a miniaturized design. In addition, when the ratio is lower than the lower limit, the thickness of each lens is excessively compressed, which is not favorable for practical production and processing; when the ratio is higher than the upper limit, the length of the module in the optical axis direction is too long, which is not favorable for miniaturization design.

-15.00＜(R22+R31)/(R22-R31)＜0；

wherein R22 is the radius of curvature of the image-side surface S5 of the second lens L2 at the optical axis, and R31 is the radius of curvature of the object-side surface S6 of the third lens L3 at the optical axis. In some of these embodiments, (R22+ R31)/(R22-R31) can be-14.00, -13.00, -12.00, -11.00, -9.00, -8.00, -2.00, or-1.00. When the above relationship is satisfied, the curvature radii of the image-side surface S5 of the second lens element L2 and the object-side surface S6 of the third lens element L3 at the optical axis can be reasonably configured, so that the deflection angle of the light beam after exiting the first lens element L1 and entering the second lens element L2 can be effectively reduced, the sensitivity of the optical assembly 10 is reduced, and the generation of ghost images can be effectively suppressed.

3.00＜f/R72＜4.00；

wherein R72 is a curvature radius of the image-side surface S15 of the seventh lens L7 at the optical axis. In some of these embodiments, f/R72 may be 3.20, 3.30, 3.40, 3.50, 3.60, 3.70, or 3.80. The image side surface S15 of the seventh lens L7 has a tendency of changing from concave to convex from the optical axis to the circumference, and this tendency of change can better balance the chromatic aberration of the off-axis field of view, and when the above relationship is satisfied, the ratio of f (total effective focal length) to R72 (the radius of curvature of the image side surface S15 of the seventh lens L7 at the optical axis) can be reasonably configured, so that the astigmatism contribution ratio of the seventh lens L7 is within a reasonable range, and the optical assembly 10 obtains good imaging quality.

2.00＜CT1/CT2＜4.00；

wherein CT1 is the thickness of the first lens element L1 on the optical axis, and CT2 is the thickness of the second lens element L2 on the optical axis. In some of these embodiments, CT1/CT2 may be 2.40, 2.60, 2.90, 3.20, 3.40, or 3.50. When the above relationship is satisfied, the central thicknesses of the first lens L1 and the second lens L2 can be optimized, the length of the optical assembly 10 in the optical axis direction can be shortened, the processing and molding of the first lens L1 and the second lens L2 are facilitated, and the molding stability is ensured.

0.05≤(T34+T56)/TTL≤0.15；

t34 is the distance between the third lens element L3 and the fourth lens element L4, T56 is the distance between the fifth lens element L5 and the sixth lens element L6, and TTL is the distance between the object-side surface S2 of the first lens element L1 and the image plane S18 of the optical device 10. In some of these embodiments, (T34+ T56)/TTL can be 0.09, 0.10, 0.11, 0.12, or 0.13. When the above relationship is satisfied, the distances between the lenses (the third lens L3 and the fourth lens L4, and the fifth lens L5 and the sixth lens L6) can be appropriately arranged, so that the length of the optical device 10 in the optical axis direction can be effectively reduced, and the optical device 10 can be easily manufactured while satisfying a high resolution.

First embodiment

In the first embodiment shown in fig. 1, the optical assembly 10 includes, in order from an object side to an image side, a stop ST0, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with positive refractive power, a sixth lens element L6 with negative refractive power, a seventh lens element L7 with negative refractive power, and an infrared filter 110. Fig. 2 is a spherical aberration diagram (mm), an astigmatism diagram (mm) and a distortion diagram (%) of the optical assembly 10 in the first embodiment, wherein the astigmatism diagram and the distortion diagram are data diagrams at a reference wavelength.

The object-side surface S2 of the first lens element L1 is convex along the optical axis, and the image-side surface S3 of the first lens element L1 is concave along the optical axis; the object-side surface S2 of the first lens element L1 is convex at the circumference, and the image-side surface S3 of the first lens element L1 is convex at the circumference. The object-side surface S4 of the second lens element L2 is convex along the optical axis, and the image-side surface S5 of the second lens element L2 is concave along the optical axis; the object-side surface S4 of the second lens element L2 is convex at the circumference, and the image-side surface S5 of the second lens element L2 is concave at the circumference. The object-side surface S6 of the third lens element L3 is convex along the optical axis, and the image-side surface S7 of the third lens element L3 is convex along the optical axis; the object-side surface S6 of the third lens element L3 is concave at the circumference, and the image-side surface S7 of the third lens element L3 is convex at the circumference. The object-side surface S8 of the fourth lens element L4 is concave along the optical axis, and the image-side surface S9 of the fourth lens element L4 is convex along the optical axis; the object-side surface S8 of the fourth lens element L4 is concave at the circumference, and the image-side surface S9 of the fourth lens element L4 is convex at the circumference. The object-side surface S10 of the fifth lens element L5 is convex along the optical axis, and the image-side surface S11 of the fifth lens element L5 is concave along the optical axis; the object-side surface S10 of the fifth lens element L5 is concave at the circumference, and the image-side surface S11 of the fifth lens element L5 is convex at the circumference. The object-side surface S12 of the sixth lens element L6 is convex along the optical axis, and the image-side surface S13 of the sixth lens element L6 is concave along the optical axis; the object-side surface S12 of the sixth lens element L6 is concave at the circumference, and the image-side surface S13 of the sixth lens element L6 is convex at the circumference. The object-side surface S14 of the seventh lens element L7 is convex along the optical axis, and the image-side surface S15 of the seventh lens element L7 is concave along the optical axis; the object-side surface S14 of the seventh lens element L7 is concave at the circumference, and the image-side surface S15 of the seventh lens element L7 is convex at the circumference.

The object-side surface and the image-side surface of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7 are aspheric.

The first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are all made of plastic.

Specifically, the optical assembly 10 satisfies the following relationship:

f/EPD＝1.59；

SD72/SD11＝2.30；

where f is the total effective focal length of the optical assembly 10, EPD is the entrance pupil diameter of the optical assembly 10, SD11 is the distance from the optical axis at the maximum effective diameter of the object-side surface S2 of the first lens L1, and SD72 is the distance from the optical axis at the maximum effective diameter of the image-side surface S15 of the seventh lens L7.

When the above-mentioned f/EPD relationship is satisfied, under the same specification of the total effective focal length, the optical element 10 has a larger entrance pupil diameter (clear aperture) to have the characteristic of a large light transmission amount, thereby improving the imaging quality in environments with insufficient light such as dusk and rainy days. In addition, since the optical assembly 10 has a larger entrance pupil diameter, accordingly, the effective half aperture of the object-side surface S2 of the first lens L1 is also enlarged, so as to cooperate with the aperture stop to make the optical assembly 10 have a larger light throughput; synchronously, the effective half aperture of the image side S15 of the seventh lens L7 becomes correspondingly larger, thereby increasing the relative illuminance of the off-axis field of view. In addition, when the relationship of SD72/SD11 is satisfied, the ratio of the effective half aperture of the image-side surface S15 of the seventh lens L7 to the effective half aperture of the object-side surface S2 of the first lens L1 can be restricted, the effective half aperture of the image-side surface S15 of the seventh lens L7 is prevented from being excessively large, and since the seventh lens L7 is closer to the image-forming surface than the other lenses, the outer diameter of the seventh lens L7 can be reduced while satisfying a large light flux amount (when being packaged with a photo chip, the module volume from the seventh lens L7 to the photo chip portion can be reduced), thereby realizing a compact design of the optical module 10.

The optical assembly 10 satisfies the following relationship:

f2/f1＝-1.99；

where f1 is the focal length of the first lens L1, and f2 is the focal length of the second lens L2. The first lens element L1 provides a stronger positive refractive power, the second lens element L2 reasonably configures a negative refractive power, and when the above relationship is satisfied, the optical assembly 10 can correct part of the spherical aberration generated by the first lens element L1, thereby improving the imaging quality; in addition, sufficient positive refractive power can be disposed at the object-side end (the first lens element L1 and the second lens element L2) of the optical element 10, so that the optical element 10 has better ability to balance field curvature, and the length of the optical element 10 in the optical axis direction can be advantageously reduced.

The optical assembly 10 satisfies the following relationship:

f123/f＝1.04；

where f123 is a combined focal length of the first lens L1, the second lens L2, and the third lens L3. The above relation is satisfied, and the cooperation of the refractive powers of the first lens element L1, the second lens element L2, and the third lens element L3 can be optimized, so that the deflection angle of light rays can be effectively controlled, and the sensitivity of the optical assembly 10 can be reduced; in addition, while balancing the aberrations, sufficient refractive power can be disposed at the object side (the first lens element L1, the second lens element L2, and the third lens element L3) to improve the image quality.

The optical assembly 10 satisfies the following relationship:

TTL/ImgH＝1.47；

wherein ImgH is a half of a diagonal length of an effective pixel area of the optical device 10 on the imaging surface S18, and TTL is a distance on the optical axis from the object side surface S2 of the first lens element L1 to the imaging surface S18 of the optical device 10. When chips of the same size (the same imaging area) are matched to form a module, the optical assembly 10 satisfying the above ratio relationship can effectively compress the length of the module in the optical axis direction, thereby realizing a miniaturized design.

The optical assembly 10 satisfies the following relationship:

(R22+R31)/(R22-R31)＝-13.17；

wherein R22 is the radius of curvature of the image-side surface S5 of the second lens L2 at the optical axis, and R31 is the radius of curvature of the object-side surface S6 of the third lens L3 at the optical axis. When the above relationship is satisfied, the curvature radii of the image-side surface S5 of the second lens element L2 and the object-side surface S6 of the third lens element L3 at the optical axis can be reasonably configured, so that the deflection angle of the light beam after exiting the first lens element L1 and entering the second lens element L2 can be effectively reduced, the sensitivity of the optical assembly 10 is reduced, and the generation of ghost images can be effectively suppressed.

The optical assembly 10 satisfies the following relationship:

f/R72＝3.36；

wherein R72 is a curvature radius of the image-side surface S15 of the seventh lens L7 at the optical axis. The image side surface S15 of the seventh lens L7 has a tendency of changing from concave to convex from the optical axis to the circumference, and this tendency of change can better balance the chromatic aberration of the off-axis field of view, and when the above relationship is satisfied, the ratio of f (total effective focal length) to R72 (the radius of curvature of the image side surface S15 of the seventh lens L7 at the optical axis) can be reasonably configured, so that the astigmatism contribution ratio of the seventh lens L7 is within a reasonable range, and the optical assembly 10 obtains good imaging quality.

The optical assembly 10 satisfies the following relationship:

CT1/CT2＝2.37；

wherein CT1 is the thickness of the first lens element L1 on the optical axis, and CT2 is the thickness of the second lens element L2 on the optical axis. When the above relationship is satisfied, the central thicknesses of the first lens L1 and the second lens L2 can be optimized, the length of the optical assembly 10 in the optical axis direction can be shortened, the processing and molding of the first lens L1 and the second lens L2 are facilitated, and the molding stability is ensured.

The optical assembly 10 satisfies the following relationship:

(T34+T56)/TTL＝0.12；

t34 is the distance between the third lens element L3 and the fourth lens element L4, T56 is the distance between the fifth lens element L5 and the sixth lens element L6, and TTL is the distance between the object-side surface S2 of the first lens element L1 and the image plane S18 of the optical device 10. When the above relationship is satisfied, the distances between the lenses (the third lens L3 and the fourth lens L4, and the fifth lens L5 and the sixth lens L6) can be appropriately arranged, so that the length of the optical device 10 in the optical axis direction can be effectively reduced, and the optical device 10 can be easily manufactured while satisfying a high resolution.

In the first embodiment, the total effective focal length f of the optical assembly 10 is 4.08mm, the aperture value FNO is 1.59, the maximum field angle FOV is 80.2 degrees (deg.), and the distance TTL from the object-side surface S2 of the first lens L1 to the image plane S18 on the optical axis is 5.17 mm.

In addition, the respective parameters of the optical assembly 10 are given by table 1 and table 2. The elements from the object plane to the image plane S18 were arranged in the order of the elements from top to bottom in table 1. The surface numbers 2 and 3 are the object-side surface S2 and the image-side surface S3 of the first lens L1, respectively, that is, the surface with the smaller surface number is the object-side surface and the surface with the larger surface number is the image-side surface in the same lens. The Y radius in table 1 is the radius of curvature of the object-side surface or the image-side surface of the corresponding surface number at the optical axis. The numerical value of the stop ST0 in the "thickness" parameter column is the distance on the optical axis from the stop ST0 to the vertex of the object-side surface S2 of the first lens L1 (the vertex refers to the intersection of the lens and the optical axis), and we default that the direction from the object-side surface of the first lens to the image-side surface of the last lens is the positive direction of the optical axis, when the value is negative, it indicates that the stop ST0 is disposed on the right side of the vertex of the object-side surface S2 of the first lens L1, and when the thickness of the stop STO is positive, the stop is on the left side of the vertex of the object-side surface of. The first value in the "thickness" parameter list of the first lens element L1 is the thickness of the lens element along the optical axis, and the second value is the distance from the image-side surface of the lens element to the object-side surface of the subsequent lens element along the optical axis. The numerical value corresponding to the plane number 17 in the "thickness" parameter of the infrared filter 110 is the distance from the image-side surface S17 to the image plane S18 of the infrared filter 110 on the optical axis. Table 2 is a table of relevant parameters of the aspherical surface of each lens in table 1, where K is a conic constant and Ai is a coefficient corresponding to the i-th high-order term in the aspherical surface type formula.

In the following examples, the refractive index and abbe number of each lens are both numerical values at a reference wavelength.

TABLE 1

TABLE 2

Second embodiment

In the second embodiment as shown in fig. 3, the optical assembly 10 includes, in order from an object side to an image side, a stop ST0, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with positive refractive power, a sixth lens element L6 with negative refractive power, a seventh lens element L7 with negative refractive power, and an infrared filter 110. Fig. 4 is a spherical aberration diagram (mm), an astigmatism diagram (mm) and a distortion diagram (%) of the optical assembly 10 in the second embodiment, wherein the astigmatism diagram and the distortion diagram are data diagrams at a reference wavelength.

In the second embodiment, the total effective focal length f of the optical assembly 10 is 4.27mm, the aperture value FNO is 1.65, the maximum field angle FOV is 77.2 degrees (deg.), and the distance TTL from the object-side surface S2 of the first lens L1 to the image plane S18 on the optical axis is 5.25 mm.

In addition, the parameters of the optical assembly 10 are given in tables 3 and 4, and the definitions of the parameters are the same as those in the first embodiment, which are not repeated herein.

TABLE 3

TABLE 4

The following data can be derived according to the provided parameter information:

third embodiment

In the third embodiment shown in fig. 5, the optical assembly 10 includes, in order from an object side to an image side, a stop ST0, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with positive refractive power, a sixth lens element L6 with negative refractive power, a seventh lens element L7 with negative refractive power, and an infrared filter 110. Fig. 6 is a spherical aberration diagram (mm), an astigmatism diagram (mm) and a distortion diagram (%) of the optical assembly 10 in the third embodiment, wherein the astigmatism diagram and the distortion diagram are data diagrams at a reference wavelength.

In the third embodiment, the total effective focal length f of the optical assembly 10 is 4.29mm, the aperture value FNO is 1.78, the maximum field angle FOV is 78 degrees (deg.), and the distance TTL from the object-side surface S2 of the first lens L1 to the image plane S18 on the optical axis is 5.2 mm.

In addition, the parameters of the optical assembly 10 are given in tables 5 and 6, and the definitions of the parameters are the same as those in the first embodiment, which are not repeated herein.

TABLE 5

TABLE 6

fourth embodiment

In the fourth embodiment as shown in fig. 7, the optical assembly 10 includes, in order from an object side to an image side, a stop ST0, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with positive refractive power, a sixth lens element L6 with positive refractive power, a seventh lens element L7 with negative refractive power, and an infrared filter 110. Fig. 8 is a spherical aberration diagram (mm), an astigmatism diagram (mm) and a distortion diagram (%) of the optical assembly 10 in the fourth embodiment, wherein the astigmatism diagram and the distortion diagram are data diagrams at a reference wavelength.

The object-side surface S2 of the first lens element L1 is convex along the optical axis, and the image-side surface S3 of the first lens element L1 is concave along the optical axis; the object-side surface S2 of the first lens element L1 is convex at the circumference, and the image-side surface S3 of the first lens element L1 is convex at the circumference. The object-side surface S4 of the second lens element L2 is convex along the optical axis, and the image-side surface S5 of the second lens element L2 is concave along the optical axis; the object-side surface S4 of the second lens element L2 is convex at the circumference, and the image-side surface S5 of the second lens element L2 is concave at the circumference. The object-side surface S6 of the third lens element L3 is concave along the optical axis, and the image-side surface S7 of the third lens element L3 is convex along the optical axis; the object-side surface S6 of the third lens element L3 is concave at the circumference, and the image-side surface S7 of the third lens element L3 is convex at the circumference. The object-side surface S8 of the fourth lens element L4 is concave along the optical axis, and the image-side surface S9 of the fourth lens element L4 is convex along the optical axis; the object-side surface S8 of the fourth lens element L4 is convex at the circumference, and the image-side surface S9 of the fourth lens element L4 is concave at the circumference. The object-side surface S10 of the fifth lens element L5 is convex along the optical axis, and the image-side surface S11 of the fifth lens element L5 is concave along the optical axis; the object-side surface S10 of the fifth lens element L5 is concave at the circumference, and the image-side surface S11 of the fifth lens element L5 is convex at the circumference. The object-side surface S12 of the sixth lens element L6 is convex along the optical axis, and the image-side surface S13 of the sixth lens element L6 is convex along the optical axis; the object-side surface S12 of the sixth lens element L6 is concave at the circumference, and the image-side surface S13 of the sixth lens element L6 is convex at the circumference. The object-side surface S14 of the seventh lens element L7 is convex along the optical axis, and the image-side surface S15 of the seventh lens element L7 is concave along the optical axis; the object-side surface S14 of the seventh lens element L7 is concave at the circumference, and the image-side surface S15 of the seventh lens element L7 is convex at the circumference.

In the fourth embodiment, the total effective focal length f of the optical assembly 10 is 4.25mm, the aperture value FNO is 1.44, the maximum field angle FOV is 77 degrees (deg.), and the distance TTL from the object-side surface S2 of the first lens L1 to the image plane S18 on the optical axis is 5.25 mm.

In addition, the parameters of the optical assembly 10 are given in tables 7 and 8, and the definitions of the parameters are the same as those in the first embodiment, which are not repeated herein.

TABLE 7

TABLE 8

fifth embodiment

In the fifth embodiment shown in fig. 9, the optical assembly 10 includes, in order from an object side to an image side, a stop ST0, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with positive refractive power, a sixth lens element L6 with negative refractive power, a seventh lens element L7 with negative refractive power, and an infrared filter 110. Fig. 10 is a spherical aberration diagram (mm), an astigmatism diagram (mm) and a distortion diagram (%) of the optical assembly 10 in the fifth embodiment, wherein the astigmatism diagram and the distortion diagram are data diagrams at a reference wavelength.

In the fifth embodiment, the total effective focal length f of the optical assembly 10 is 4.35mm, the aperture value FNO is 1.9, the maximum field angle FOV is 76.2 degrees (deg.), and the distance TTL from the object-side surface S2 of the first lens L1 to the image plane S18 on the optical axis is 5.3 mm.

In addition, the parameters of the optical assembly 10 are given in tables 9 and 10, and the definitions of the parameters are the same as those in the first embodiment, which are not repeated herein.

TABLE 9

Watch 10

sixth embodiment

In the sixth embodiment shown in fig. 11, the optical assembly 10 includes, in order from an object side to an image side, a stop ST0, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with negative refractive power, a sixth lens element L6 with positive refractive power, a seventh lens element L7 with negative refractive power, and an infrared filter 110. Fig. 12 is a spherical aberration diagram (mm), an astigmatism diagram (mm) and a distortion diagram (%) of the optical assembly 10 in the sixth embodiment, wherein the astigmatism diagram and the distortion diagram are data diagrams at a reference wavelength.

The object-side surface S2 of the first lens element L1 is convex along the optical axis, and the image-side surface S3 of the first lens element L1 is concave along the optical axis; the object-side surface S2 of the first lens element L1 is convex at the circumference, and the image-side surface S3 of the first lens element L1 is convex at the circumference. The object-side surface S4 of the second lens element L2 is convex along the optical axis, and the image-side surface S5 of the second lens element L2 is concave along the optical axis; the object-side surface S4 of the second lens element L2 is convex at the circumference, and the image-side surface S5 of the second lens element L2 is concave at the circumference. The object-side surface S6 of the third lens element L3 is convex along the optical axis, and the image-side surface S7 of the third lens element L3 is convex along the optical axis; the object-side surface S6 of the third lens element L3 is concave at the circumference, and the image-side surface S7 of the third lens element L3 is convex at the circumference. The object-side surface S8 of the fourth lens element L4 is concave along the optical axis, and the image-side surface S9 of the fourth lens element L4 is convex along the optical axis; the object-side surface S8 of the fourth lens element L4 is convex at the circumference, and the image-side surface S9 of the fourth lens element L4 is concave at the circumference. The object-side surface S10 of the fifth lens element L5 is convex along the optical axis, and the image-side surface S11 of the fifth lens element L5 is concave along the optical axis; the object-side surface S10 of the fifth lens element L5 is concave at the circumference, and the image-side surface S11 of the fifth lens element L5 is convex at the circumference. The object-side surface S12 of the sixth lens element L6 is convex along the optical axis, and the image-side surface S13 of the sixth lens element L6 is convex along the optical axis; the object-side surface S12 of the sixth lens element L6 is concave at the circumference, and the image-side surface S13 of the sixth lens element L6 is convex at the circumference. The object-side surface S14 of the seventh lens element L7 is convex along the optical axis, and the image-side surface S15 of the seventh lens element L7 is concave along the optical axis; the object-side surface S14 of the seventh lens element L7 is convex at the circumference, and the image-side surface S15 of the seventh lens element L7 is convex at the circumference.

In the sixth embodiment, the total effective focal length f of the optical assembly 10 is 4.2mm, the aperture value FNO is 1.7, the maximum field angle FOV is 78 degrees (deg.), and the distance TTL from the object-side surface S2 of the first lens L1 to the image plane S18 on the optical axis is 5.12 mm.

In addition, the parameters of the optical assembly 10 are given in tables 11 and 12, and the definitions of the parameters are the same as those in the first embodiment, which are not repeated herein.

TABLE 11

TABLE 12

seventh embodiment

In the seventh embodiment shown in fig. 13, the optical assembly 10 includes, in order from an object side to an image side, a stop ST0, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with positive refractive power, a sixth lens element L6 with positive refractive power, a seventh lens element L7 with negative refractive power, and an infrared filter 110. Fig. 14 is a spherical aberration diagram (mm), an astigmatism diagram (mm) and a distortion diagram (%) of the optical assembly 10 in the seventh embodiment, wherein the astigmatism diagram and the distortion diagram are data diagrams at a reference wavelength.

In the seventh embodiment, the total effective focal length f of the optical assembly 10 is 4.24mm, the aperture value FNO is 1.58, the maximum field angle FOV is 77.6 degrees (deg.), and the distance TTL from the object-side surface S2 of the first lens L1 to the image plane S18 on the optical axis is 5.14 mm.

In addition, the parameters of the optical assembly 10 are given in tables 13 and 14, and the definitions of the parameters are the same as those in the first embodiment, which are not repeated herein.

Watch 13

TABLE 14

as shown in fig. 15, in some embodiments, the image capturing module 20 includes an optical assembly 10 and a photosensitive chip 210 disposed on an image side of the optical assembly 10. Specifically, in some embodiments, the photosensitive chip 210 is disposed on the imaging surface S18 of the optical assembly 10. In some embodiments, the photosensitive chip 210 may be a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). After the optical assembly 10 is adopted, the image capturing module 20 has a larger light transmission aperture to obtain a larger light transmission amount, and still has better imaging quality under the condition of insufficient ambient light.

The light ray carrying the image information of the object enters the optical assembly 10 from the object side of the optical assembly 10, passes through the stop ST0, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7 and the infrared filter 110 in sequence, reaches the photosensitive element 210, and is received by the photosensitive element 210. At this time, the image information is converted from the optical signal into an electrical signal, and the electrical signal is transmitted to the image processor through the circuit board electrically connected to the photo chip 210.

In some embodiments, the image capturing module 20 further includes a fixing member for fixing the optical assembly 10 and the photosensitive chip 210. The optical assembly 10 and the photosensitive chip 210 are disposed opposite to each other in the fixing member by dispensing. In some embodiments, the fixing member has an integrated structure, and the optical element 10 and the photosensitive element 210 are relatively fixedly disposed, and the image capturing module 20 is a fixed focus camera module.

In some embodiments, the fixing member includes a first fixing member and a second fixing member, which are independent from each other, the first fixing member fixes the optical assembly 10, and the second fixing member fixes the photosensitive chip 210. In some embodiments, the first fixing element and the second fixing element are relatively fixed, that is, the optical element 10 and the photosensitive chip 210 are relatively fixed, and the image capturing module 20 can be used as a fixed-focus camera module. In other embodiments, the image capturing module 20 is further provided with a voice coil motor, and the voice coil motor is respectively connected to the first fixing element and the second fixing element, so that the first fixing element can move relative to the second fixing element, and thus the optical assembly 10 can move relative to the photosensitive chip 210 under the action of the voice coil motor, and the image capturing module 20 has a focusing function.

As shown in fig. 16, the image capturing module 20 can be applied to the mobile terminal 30. The mobile terminal 30 may be an electronic device such as a miniaturized smart phone, a camera phone, a digital camera, a game machine, a tablet computer, and a PC, or may be a camera lens in a home appliance having a camera function. In some embodiments, the image capturing module 20 may be a front camera or a rear camera of the mobile terminal 30.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. An optical assembly, comprising, in order from an object side to an image side:

a fourth lens element with refractive power;

a fifth lens element with refractive power;

a sixth lens element with refractive power;

the optical assembly further satisfies the following relationship:

f/EPD＜2.0；

2. The optical assembly of claim 1, wherein the optical assembly satisfies the following relationship:

1.50＜SD72/SD11＜3.00；

wherein SD11 is the distance from the optical axis at the maximum effective diameter of the object side surface of the first lens, and SD72 is the distance from the optical axis at the maximum effective diameter of the image side surface of the seventh lens.

3. The optical assembly of claim 1, wherein the optical assembly satisfies the following relationship:

f2/f1＜-1.00；

wherein f1 is the focal length of the first lens, and f2 is the focal length of the second lens.

4. The optical assembly of claim 1, wherein the optical assembly satisfies the following relationship:

0＜f123/f＜2.00；

wherein f123 is a composite focal length of the first lens, the second lens, and the third lens.

5. The optical assembly of claim 1, wherein the optical assembly satisfies the following relationship:

1.20＜TTL/ImgH＜2.00；

wherein ImgH is a half of a diagonal length of an effective pixel area of the optical assembly on an imaging surface, and TTL is a distance on an optical axis from an object-side surface of the first lens element to the imaging surface of the optical assembly.

6. The optical assembly of claim 1, wherein the optical assembly satisfies the following relationship:

-15.00＜(R22+R31)/(R22-R31)＜0；

wherein R22 is a curvature radius of the image side surface of the second lens at the optical axis, and R31 is a curvature radius of the object side surface of the third lens at the optical axis.

7. The optical assembly of claim 1, wherein the optical assembly satisfies the following relationship:

3.00＜f/R72＜4.00；

wherein R72 is a radius of curvature of an image-side surface of the seventh lens element at an optical axis.

8. The optical assembly of claim 1, wherein the optical assembly satisfies the following relationship:

2.00＜CT1/CT2＜4.00；

wherein CT1 is the thickness of the first lens element on the optical axis, and CT2 is the thickness of the second lens element on the optical axis.

9. The optical assembly of claim 1, wherein the optical assembly satisfies the following relationship:

0.05≤(T34+T56)/TTL≤0.15；

wherein T34 is a distance between the third lens element and the fourth lens element on the optical axis, T56 is a distance between the fifth lens element and the sixth lens element on the optical axis, and TTL is a distance between the object-side surface of the first lens element and the image plane of the optical assembly on the optical axis.

10. An image capturing module, comprising a photosensitive element and the optical assembly of any one of claims 1 to 9, wherein the photosensitive element is disposed on an image side of the optical assembly.

11. A mobile terminal, comprising the image capturing module of claim 10.